OCR Text |
Show __9__ that this relation might be that low flow periods may be as much as twice the length of a period of higher flows. It would appear from this hydrograph that history seems to be repeating itself, since a definite period of low flows is indicated both at the beginning and the end of this 60-year period of observation; and this tends to show that a period of higher flow is probable, perhaps at some not too distant future time. In this connection, by assuming that a coming period of higher flow may approximate the past period, the running average of annual flows taken in reverse may be instructive. The line colored in green below this first running average curve back as far as the year 1908, is this new revision of a running average curve. It covers the same total 60-year period and ends with the same figure of 15,260,000 acre feet. However, it is significant that this curve is below the first running average curve for all but the last twelve years, those being the first twelve years used in computing the first curve. The approximate time for the beginning of a period of higher flow may be indicated by certain considerations in connection with this new curve. Assume first, that we are now twenty-five years away from the minimum year of 1954 in the upward trend, which is continuous to the left of year 1930 on this diagram. In other words, assume that in 1955 we have reached an average of about 13,-120,000. According to this curve, in the next ten years the average would have increased to about 14,500,000 acre feet, and in another ten years, it would have reached more than 15,000,000 acre feet. The maximum running average in reverse would have been reached in a total of fifty years, counting from the minimum of 1954. Returning now to the beginning of this reversed curve, note |
Source |
Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : |